A while back before Windy Whistles was revealed to be Rainbow Dash’s mom, I headcanon’d that Firefly was her mother; As did many.  
That headcanon got flushed when Bow and Windy were introduced.. However, I still wanted to keep Firefly in my headcanon.

So I put her as Rainbow’s Grandmare/Grandma instead. I headcanon Firefly is Windy Whistles mom, instead of Bows. (I’ll explain why later) Firefly in my headcanon was a Wonderbolt, and Windy’s supportive nature came from cheering her mother on, and Firefly teaching her that she could do anything she wanted to do. They supported each other, and that support never faded away.

But that got me thinking about Bow… Who would his mother be? And one look at his rainbow mane and I knew that the rainbow mane coloration was a genetic, dominant trait… So who else could be his mother than the original Rainbow Dash! (Renamed to Rainbow Shine, because I felt it suited her more)

Using a picture of the Generation 1 Rainbow Dash, I recreated her design to fit the Gen 4 style. I imagined she was a very beautiful mare still; Raising a rough-housing, mischievous little colt on her own; Young Bow was quite the hoof-full for a fashion mare like her to handle, but she was a good mother and tried her best to always be there for her son.. Even when she wasnt sure how to be sometimes.   
I kept Rainbow as an earth pony; As she was in the original. That makes her all the more respected for raising a little pegasus on her own.  
I figured Rainbow being a single parent would make more of an impact on Bow’s confidence and support towards other ponies and her growing up.

As for Windy’ dad… No clue yet lol He’s probably some weather pony Firefly met in Flight School lol

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Feel free to add this to your headcanon as well!   
Really I just wanted to doll them today lol

(Little baby Bow and Windy are so cute!! <3)